The field of the present invention is that of polyorganosiloxanes containing one or a number of functionalities introduced by substituents of the silicon and conferring specific properties on the polymers, for example antiadhesive, lubricating or compatibilizing properties and the like, which are much sought after in silicone applications.
More precisely, the present invention relates to a multifunctionalized polyorganosiloxane in which the functionalities are each carried by different siloxy units, via an SiC or SiOC bond.
The present invention also relates to a process for the functionalization of polyorganosiloxanes which makes it possible, in particular, to result in the multifunctionalized polyorganosiloxanes targeted above.
The functionalization of the polyorganosiloxanes can conventionally be carried out by substitution of the hydrogens carried by the silicon atoms of the chain.
According to a first route, this substitution can consist of a hydrosilylation reaction between a polyorganohydrosiloxane and an olefinic reagent carrying at least one xcfx80 double bond capable of reacting with the hydrogen according to an addition mechanism. Hydrosilylation is a reaction which is fully known in the technical field under consideration. This reaction is usually catalysed with platinum. It is widely described in the literature. In this respect, reference may be made, for example, to the article by V. M. Kopilov et al., Z. Obsh. Khim., vol. 57 (5), (1987) p. 1117-1127. In this first route, all the silicon atoms containing available hydrogen are substituted by organic units via SiC bonds, the said organic units being introduced by the olefinic reactant(s). One illustration, among others, of hydrosilylation is given in European Patent Application No. 504,800, which describes the addition of a polyoxyalkylene substituted by an olefinic group (vinyl) to a polydimethylhydrosiloxane of formula:
Me3SiOxe2x80x94(Me2SiO)157xe2x80x94(MeHSiO)21xe2x80x94SiMe3(Mexe2x95x90CH3),
in the presence of a monocarboxylic ester of a solvent of the alkanediol type. In this case, it clearly seems that a single type of functionalization can be envisaged and only the groups capable of being substituted by olefinic residues can be grafted onto the polyorganosiloxane.
A second functionalization route is that according to which the silicons of the polyorganosiloxane concerned are substituted by functional residues bonded to the polyorganosiloxane by virtue of SiOC bridges. The reactions which can be envisaged for doing this are, for example, those involving xcex1,xcfx89-chlorosiloxanes and alcohols or alternatively polyorganohydrosiloxanes and alcohols according to a dehydrogenation/condensation mechanism.
These dehydrogenation/condensation reactions, also described as alcoholyses of organohydropolysiloxanes, are described in particular in S. Koama and Y. Humeki, Journal of Applied Polymer Science, Vol.21 (277), pages 863-867.
This article refers to polymethylhydrosiloxanes brought into contact with an alcohol of the methanol or ethanol type and of a catalyst chosen from bases and certain metal chlorides (Lewis acids). The solvent employed is benzene. The writers thus obtain a polyalkoxymethylsiloxane which itself also has only one functionality.
Record has also been had to dehydrogenation/condensation in the invention described by U.S. Pat. No. 5,310,842 relating to alkoxy-substituted polyorganosiloxanes. These products comprise dimethylsiloxy and methylalkoxysiloxy units and contain from 4 to 30 carbon atoms. The catalyst employed in this dehydrogenation/condensation is platinum-containing in nature (chloroplatinic acid). All the starting methylhydrosiloxy functionalities are converted (degree of conversion greater 99%) to alkoxy-substituted units. The alkoxylated side chains are involved in the compatibilization of the polyorganosiloxanes with other products such as, for example, organic polymers, with which they are used in the final applications. Although the writers maintain that these alkoxylated polyorganosiloxanes have good resistance to hydrolysis, it may be permitted to doubt this, taking into account the not insignificant sensitivity of the oxygen bridge in this respect. In addition, this prior invention retains the disadvantage of the monofunctionalization of the polyorganosiloxane.
This review of the prior art makes it appear that multifunctionalized polyorganosiloxanes are lacking. Such products would nevertheless be highly appreciable in certain uses of silicones, because it is obvious that the multifunctionalization only causes an increase in the potentialities of these products which are already very wide-ranging. The introduction of multiple functionalities by grafting would also provide the undeniable advantage of making it possible to construct silicones to measure, specifically suited to the targeted applications.
In the light of this irrefutable fact, one of the essential objects of the present invention is to provide a functionalized polyorganosiloxane, in particular a multifunctionalized polyorganosiloxane, and more particularly still a polyorganosiloxane comprising at least two siloxy sites (or units) of different functionalization, each carrying one type of functionality, corresponding to a plurality of functional types.
Another essential object of the invention is to provide a polyorganosiloxane which can be obtained simply and economically.
Another object of the present invention is to provide a monofunctionalized precursor which makes it possible to gain access to multi-, and in particular bifunctionalized, polyorganosiloxanes.
Another essential object of the invention is to provide a process for the preparation of polyorganosiloxanes having simultaneously a number of types of functional groups introduced by grafting, in particular two types of functional groups, it being necessary for the said process to be easy to implement and with a low cost price, both as regards the raw materials employed and as regards the equipment, energy and time required.
Another essential object of the invention is to provide a process for the synthesis of a precursor or of an intermediate product which makes it possible to result in the multifunctional, in particular bifunctional, polyorganosiloxanes targeted above.
In seeking to meet these objectives, the Applicant Company has discovered in an entirely surprising and unexpected way, after many studies and experiments, that, in contrast to what is taught by Koama and Humeki, the alcoholysis of polymethylhydrosiloxanes results, under certain conditions, in alkoxy-substituted siloxy units and in hydrosiloxy units in which the hydrogen has not reacted, according to a specific stoichiometry.
It follows that the present invention, which makes it possible to achieve the abovesaid objectives among others, relates, as new product per se, to a functionalized polyorganosiloxane, and more particularly a multifunctionalized polyorganosiloxane, comprising, per molecule,
xcex1xe2x80x94on the one hand, at least one functional siloxy unit of formula:                                           (            R            )                    a                ⁢                              YSi            ⁡                          (              O              )                                                          3              -              a                        2                                              (        I        )            
xe2x80x83in which
a=0, 1 or 2
R is a monovalent hydrocarbon radical chosen from linear or branched alkyls having from 1 to 6 atoms, in particular methyl, ethyl, propyl or butyl, and/or from aryls and in particular phenyl, methyl being more particularly preferred, the R radicals being identical or different when a=2,
Y is a linear or branched alkoxy radical preferably chosen from C1-C15 alkoxys, in particular C1-C6 alkoxys, methoxy, ethoxy and (iso)propoxy being more particularly used,
xcex2xe2x80x94and, on the other hand, at least one functional siloxy unit of formula:                                           (            R            )                    b                ⁢                              WSi            ⁡                          (              O              )                                                          3              -              b                        2                                              (        II        )            
xe2x80x83in which
b=0, 1 or 2,
R corresponds to the same definition as that given above for the R substituent of the unit (I) and can be identical to or different from the latter,
W is hydrogen or a monovalent hydrocarbon radical having from 2 to 30 carbon atoms and optionally S and/or O and/or halogen atoms and constituting a functional residue, bonded to the silicon via an Sixe2x80x94C bond,
this residue preferably being chosen from the following groups:
(i) an alkyl, aralkyl or aryl group substituted by one or a number of halogen atom(s) and/or by a mono- or polyhaloalkyl radical,
(2i) a polyether ether group of formula
xe2x80x94(R1xe2x80x94Oxe2x80x94)exe2x80x94R2
xe2x80x83with
R1 representing an alkylene group and,
R2 representing a hydrogen atom or an alkyl group
and e=1 to 5,
(3i) an epoxy group resulting from the union of an oxygen atom with two carbon atoms belonging to an alkyl, cycloalkyl or alkenyl group,
(4i) an alkoxyalkyl or aryloxyalkyl group,
(5i) a mono- or polyhydroxylated and/or mono- or polycarbonylated and/or mono- or polyesterified alkyl group,
(6i) a sterically hindered phenol group or a group deriving from a mono- or dihydroxylated benzophenone,
(7i) an alkoxysilyl, preferably trialkoxysilyl, group,
xcex3xe2x80x94and, optionally, at least one siloxy unit (III) of following formula:                                           (            R            )                    c                ⁢                              (            H            )                    d                ⁢                              Si            ⁡                          (              O              )                                                          4              -                              (                                  c                  +                  d                                )                                      2                                              (        III        )            
xe2x80x83in which
c=0, 1, 2 or 3, d=0 or 1 and c+dxe2x89xa63,
the R substituents being as defined above in the units (I) and (II).
To the knowledge of the Applicant Company, no document of the prior art describes polyorganosiloxanes having at the same time units functionalized by a functional residue bonded to the silicon via an SiOC bond and siloxy units functionalized by a functional residue bonded to the silicon via an SiC bond.
In this polyorganosiloxane according to the invention, the first alkoxy functionality Y is carried by the units of formula (I), whereas the second hydrocarbon functionality W appears in the units of formula (II) defined above.
As regards W, the specific case in which this radical corresponds to hydrogen is that illustrating the polyorganosiloxane which is the precursor of the multifunctional polyorganosiloxane and which constitutes another subject of the invention.
According to the usual terminology in silicones, these units (I) and (II) can be M, D but also T units. The presence of T units corresponds to an alternative form in which the polyorganosiloxanes exist in the form of linear chains crosslinked to one another.
The Y functional groups are characterized in that they can be hydrolysed and in that they can therefore make it possible to graft onto various substrates, which can be particularly advantageous in certain applications, e.g. antiadhesion, lubrication and the like.
W can consist of a hydrocarbon functional group which is more difficult to hydrolyse and which is capable of expressing various properties according to its chemical nature. This can be the compatibilization with organic polymers or alternatively the introduction of a crosslinking functional group into the polyorganosiloxane.
In accordance with an advantageous form of the invention, this functional substituent W is chosen from the following radicals:
a linear a alkyl radical having from 8 to 12 carbon atoms, in particular radicals with halogenated functional residues (type (i)) and of formula: 
a radical with a halogenated (type (i)) and etherified (type (2i)) functional residue and of formula: 
a (poly)etherified radical of type (2i) and of formula: 
a radical of type (3i), and of formula: 
an aryloxyalkyl radical of type (4i) and of formula: 
an esterified alkyl radical of type (Si) and of formula: 
a radical of type (6i) and of formula: 
a radical of type (7i) and of formula: 
As indicated above, the invention is not limited to the case in which the polyorganosiloxane contains only two types of functionality Y and W. Indeed, according to an advantageous alternative form, the polyorganosiloxane contains, in addition to the units (I) and (II), at least one unit (III).
These SiH units (III) are, for example, residual siloxy sites in which the hydrogen has not reacted in order to be substituted by Y or W. This residual hydrogenated nature can prove to be useful in certain applications of polyorganosiloxanes according to the invention.
It should be emphasized that from the moment that a unit of a given type (I, II or III, e.g.) is present in the polyorganosiloxane in more than one form, the various forms can be identical to or different from one another.
Taking into account the values which the indices a to d attributed to the substituents in the units (I), (II), (III) can take, it should be understood that the polyorganosiloxanes according to the invention can have a linear and/or branched and/or cyclic structure.
The preferred R radicals are: methyl, ethyl, n-propyl, isopropyl or n-butyl, preferably methyl. More preferentially still, at least 80 % by number of the R radicals are methyls.
The preferred alkoxy radicals Y are the ethoxy radicals.
In order to be even more specific as regards the polyorganosiloxanes to which the invention relates, as new products, mention is first of all made of those formed by statistical, sequenced or block linear copolymers of following average formula: 
in which:
the symbols Y, W and R are as defined above,
the symbol Z is a monovalent radical chosen from the radicals formed by hydrogen and from those corresponding to the definitions of R, Y and W,
the indices m, n, p and q represent positive whole or decimal numbers and
the sum m+n+p+qxe2x89xa73, preferably between 3 and 100,
the scenario in which p=q=0, mxe2x89xa71 and nxe2x89xa650 being more particularly preferred,
0xe2x89xa6mxe2x89xa6100, preferably 1xe2x89xa6mxe2x89xa650
0xe2x89xa6nxe2x89xa6100, preferably 1xe2x89xa6nxe2x89xa650
0xe2x89xa6pxe2x89xa620, preferably 0xe2x89xa6pxe2x89xa610
0xe2x89xa6qxe2x89xa640, preferably 0xe2x89xa6qxe2x89xa620
with the conditions according to which:
if m=0, at least one of the Z substituents corresponds to a radical corresponding to the definition characterizing Y,
if n=0, at least one of the Z substituents corresponds to a radical corresponding to the definition characterizing W,
and if m=n=0 and p+qxe2x89xa71, then one of the Z substituents corresponds to a radical corresponding to the definition characterizing Y
and the other of the Z substituents corresponding to the definition characterizing W.
Mention may be made, among the more particularly preferred polyorganosiloxanes of the formula (IV), of those in which p=q=0 and 0.1xe2x89xa6m/nxe2x89xa65, preferably 1xe2x89xa6m/nxe2x89xa65 and more preferentially 1.5xe2x89xa6m/n xe2x89xa63.
An alternative to the linear structure of the polymers of formula (IV) defined above relates to the polyorganosiloxanes consisting of cyclic copolymers of following average formula: 
in which Y, W and R are as defined above,
and with r, s, t and u representing positive whole or decimal numbers:
the sum r+s+t+uxe2x89xa73, preferably between 3 and 8, the scenario in which t=u=0 being more particularly preferred,
1xe2x89xa6rxe2x89xa68, preferably 1xe2x89xa6rxe2x89xa64
1xe2x89xa6sxe2x89xa68, preferably 1xe2x89xa6sxe2x89xa64
0xe2x89xa6txe2x89xa68, preferably 0xe2x89xa6txe2x89xa64
0xe2x89xa6uxe2x89xa68, preferably 0xe2x89xa6uxe2x89xa64.
The polyorganosiloxanes according to the invention preferably consist of the products corresponding to those in which R =CH3 and p=u=0 in the formulae (IV) and (V) defined above.
It is obvious that in these formulae (IV) and (V), as already indicated above, the W radicals can be identical or different in nature when n greater than 1 and S greater than 1.
The mixtures of polyorganosiloxanes of the type of those defined above come within the context of the present invention.
According to another of its aspects, this invention is targeted at a process for the preparation of functionalized polyorganosiloxanes, in particular multifunctionalized polyorganosiloxanes, which can in particular be those described above.
This functionalization process advantageously consists essentially in reacting
a starting polyorganosiloxane comprising units of formula (II) as defined above, in which W represents hydrogen, with
at least one alcohol from which the functionality Y of the unit (I) derives, and which is useful both as reactant and as reaction solvent, in the presence of a catalyst, at least one of the active elements of which is chosen from the transition metals, according to a dehydrogenation/condensation mechanism (1st stage).
One of the novel features of this process lies in the use of the alcohol corresponding to the Y group, both as reactant and as reaction solvent in this dehydrogenation/condensation stage. This is one of the essential differences from the known alcoholysis method according to Koama and Humeki. In accordance with the invention, it was possible to observe that, whatever the amount of alcohol used in the process, it is not possible to convert all the SiW functional groups with W=H of the starting polyorganosiloxane. Thus, after a certain limit degree of conversion, which varies according to the reaction conditions, the stoichiometry and the nature of the reactants, the residual SiH groups become inactive with respect to dehydrogenation/condensation. For example, in the presence of ethanol, the degree of conversion of the initial SiH functional groups levels out at 66%.
This novel dehydrogenation/condensation therefore results in a polyorganosiloxane containing at least one related functionality and free SiH functional groups. It is a precursor or an intermediate product which constitutes by itself and as such a new product per se in accordance with the invention. This precursor or this intermediate product will allow access to the multifunctional polyorganosiloxane, the preparation of which will be described in detail below.
The starting polyorganosiloxane is advantageously selected from those corresponding to the following average formula: 
in which:
the R symbols are identical or different and are as defined in the legend to the formula of the units (I) and (II),
the Zxe2x80x2 symbols are identical or different and correspond to R or to hydrogen,
p corresponds to the same definition as that given above in the legend to the formula (IV),
v=m+n+q,
with the condition according to which, if v=0, then pxe2x89xa71 and the two Zxe2x80x2 radicals correspond to hydrogen.
The starting polyorganohydrosiloxanes which are used, for example, in the preparation of the cyclic functionalized products are those selected from those corresponding to the following average formula: 
in which:
the R symbols are identical or different and are as defined in the legend to the formula of the units (I) and (II),
u corresponds to the same definition as that given above in the legend to the formula (V),
y=r+s+t and y+uxe2x89xa73.
The alcohols employed are preferably linear or branched monohydroxylated alkanols (primary, secondary or tertiary alkanols, preferably primary alkanols) preferably chosen from the following list: methanol, ethanol, (iso)propanol or (n-)butanol, ethanol being preferred.
As regards the catalyst, it is advantageously chosen from those containing at least one of the following elements: Pt, Rh, Ru, Pd, Ni and their combinations, this catalyst optionally being coupled to a support, which may or may not be inert.
According to a preferred arrangement of the invention, the catalyst is taken from the family of the platinum catalysts conventionally used for carrying out hydrosilylation reactions. These platinum catalysts are fully described in the literature. Mention may in particular be made of the complexes of platinum and of an organic product described in U.S. Pat. Nos. 3,159,601, 3,159,602, and 3,220,972 and European Patents EP-A-57,459, EP-188,978 and EP-A-190,530 and of the complexes of platinum and of vinylated organopolysiloxane described in U.S. Pat. Nos. 3,419,593, 3,715,334, 3,377,432 and 3,814,730. The Karstedt catalyst is an example of a platinum catalyst which is suitable for the process according to the invention (U.S. Pat. No. 3,775,452, Karstedt).
The nickel-based catalysts, such as for example Raney nickel, are a possible alternative to the platinum catalysts.
As regards the reaction conditions, the dehydrogenation/condensation can be carried out over a wide temperature range extending, for example, from 0 to 200xc2x0 C., but it is clear that it is preferable to carry it out at a temperature between 20 and 80xc2x0 C. and preferably between 40 and 70xc2x0 C.
The second stage of the process according to the invention consists in preparing a multifunctionalized polyorganosiloxane from the precursor or intermediate polyorganosiloxane produced by dehydrogenation/condensation, as explained above.
To do this, the polyorganosiloxane which has been converted by dehydrogenation/condensation is reacted with at least one olefinic compound carrying at least one r bond, so as to make it possible for the converted polyorganosiloxane to add to this olefinic compound according to a hydrosilylation mechanism, in the presence of a catalyst and, preferably, at a temperature between 5 and 100xc2x0 C. and more preferentially still between 20 and 90xc2x0 C. This hydrosilylation therefore follows the dehydrogenation/condensation.
According to preferred methodology, the hydrosilylation is initiated by adding the olefinic compound, comprising the W radical as defined above, to the intermediate alkoxylated polyorganosiloxane, once the dehydrogenation/condensation has been completed.
In practice, this addition can take place when hydrogen evolution has ceased.
The reactive alkene can be formed by a mixture of products containing just one or a number of types of W radicals, which determine the multifunctionality of the final polyorganosiloxane.
In the case where a number of W types are provided, the alkene corresponding to the second functionality is preferably allowed to react first, then, once this alkene has completely reacted, the alkene corresponding to the third functionality is incorporated, and so on.
Instead of being added to the reaction mixture after the dehydrogenation/condensation, the olefinic compound which is the precursor of W can be used before beginning this first stage of the process, or alternatively during the latter.
According to a preferred characteristic of the invention, it is arranged for the hydrosilylation to be catalysed by at least a part of the dehydrogenation/condensation catalyst and preferably exclusively by this catalyst.
This is one of the particularly advantageous and unexpected aspects of the process of the invention. Indeed, it is entirely surprising to observe that the dehydrogenation/condensation catalyst, preferably of platinum nature, is still active in this second hydrosilylation stage.
Indeed, it is certainly known that the catalyst experiences a degree of deterioration in its performance during dehydrogenation/condensation. However, what is still more surprising is that the catalyst is present in the post-dehydrogenation/condensation medium containing polyorganosiloxanes carrying residual SiH groups. Now, in theory and according to a prejudice which is widespread in the field under consideration, the hydrosilylation catalyst, in particular a platinum catalyst, is only active if it is first brought into the presence of the reactive product comprising at least one r bond, so that the formation of an inactive colloid ought to have been observed in the case of the invention. However, none is observed.
In contrast, the residual SiH groups are particularly reactive, with respect to olefinic compounds added, by virtue of the effect of the hydrosilylation catalyst, which is itself also entirely effective. This result makes it possible to obtain, in a single sequence and without changing the reactor, a polyorganosiloxane containing a number of different functionalities.
The olefinic compounds used can be easily deduced from the definition of W given above. The choice as regards this radical is determined by the targeted applications (one or a number of different functionalities).
The hydrosilylation stage can advantageously take place at room temperature and in bulk or in solution, for example in the alcohol which was used as solvent and as reactant in the dehydrogenation/condensation reaction.
At the end of the reactions, the crude polyorganosiloxanes which are obtained can be purified, in particular by passing through a column filled with an ion exchange resin and/or by simple evaporation of the excess reactants introduced and optionally of the solvent used by heating between 100 and 180xc2x0 C. under reduced pressure.
According to another of its aspects, the present invention relates to the application of the polyorganosiloxanes defined above, and of those obtained by the process which is also described above, as antiadhesion modulator and/or crosslinking agent in silicone compositions or alternatively as treatment agent for inorganic fillers, such as silica, carbonates, carbon black, and the like.
In particular, these polyorganosiloxanes can be employed as additives for surface treatment compositions, in particular for paper, concrete, metal, and the like,
the said compositions advantageously being varnishes, paints, antiadhesive coatings, and the like.
Another subject of the present invention is compositions, for example silicones, comprising the polyorganosiloxanes described above as active ingredients. To be more precise, mention may be made of;
antiadhesive compositions for paper,
lubricating compositions,
compositions containing organic polymers and the polyorganosiloxanes under consideration provided with compatibilizing functionalities.